Notes:
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1) The parsed source material can only come from somewhere in
the TemplateRoot tree for security reasons. There is no way
around this. If you want to include content from elsewhere on
your disk, use a link from somewhere under Template Root to that
content.
2) There is a limited parse depth. It is set as a property
"directive.parse.max.depth = 10" by default. This 10 deep
limit is a safety feature to prevent infinite loops.